JP2012151512A - Nitride semiconductor light-emitting element and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitride semiconductor light-emitting element capable of obtaining sufficient optical output, and to provide a method of manufacturing the same.SOLUTION: A nitride semiconductor light-emitting element comprises: a first cladding layer 13 having an n-type nitride semiconductor; an active layer 14 that is formed on the first cladding layer 13 and has a nitride semiconductor containing In; a GaN layer 17 formed on the active layer 14; a first AlGaN layer 18 that is formed on the GaN layer 17 and has a first Al composition ratio x1; a p-type second AlGaN layer 19 that is formed on the first AlGaN layer 18, has a higher second Al composition ratio x2 than the first Al composition ratio x1, and contain a larger quantity of Mg than the GaN layer 17 and the first AlGaN layer 18; and a second cladding layer 20 that is formed on the second AlGaN layer 19 and has a p-type nitride semiconductor.

Description

  The present invention relates to a nitride semiconductor light emitting device and a method for manufacturing the same.

  Conventionally, a nitride semiconductor light emitting device has a Mg-doped p-type AlGaN layer formed on an active layer having a nitride semiconductor containing In as an electron barrier layer for confining electrons in the active layer. (For example, refer to Patent Document 1 or Patent Document 2).

In the nitride semiconductor light emitting device of Patent Document 1, a p-type AlGaN layer is a first p-type formed by MOCVD (Metal Organic Chemical Vapor Deposition) method using N ₂ gas so as to suppress degradation of the active layer. And an AlGaN layer and a second p-type AlGaN layer formed by MOCVD using H ₂ gas so as to form a barrier potential.

  However, in this nitride semiconductor light emitting device, the first p-type AlGaN layer has an Al composition ratio substantially equal to or higher than that of the second p-type AlGaN layer, and a large amount for reducing the bulk resistance. Mg is doped.

  As a result, when forming the second p-type AlGaN layer, there is a problem that Mg is excessively diffused into the active layer and the quality of the active layer is lowered.

  In the nitride semiconductor light emitting device of Patent Document 2, an intermediate layer made of undoped GaN, AlGaN, or the like is provided between the active layer and the p-type AlGaN layer so as to suppress excessive diffusion of Mg into the active layer. is doing.

  However, in this nitride semiconductor light emitting device, the temperature of the substrate is raised while growing an intermediate layer on the active layer. As a result, there is a problem that the thermal degradation of the active layer occurs during the temperature rise and the quality of the active layer is lowered.

  Therefore, any of the nitride semiconductor light emitting devices has a problem that the light emission efficiency is lowered and a sufficient light output cannot be obtained.

Japanese Patent No. 3446660 JP 2006-261392 A

  The present invention provides a nitride semiconductor light emitting device capable of obtaining a sufficient light output and a method for manufacturing the same.

A nitride semiconductor light-emitting device of one embodiment of the present invention includes a first cladding layer having an n-type nitride semiconductor, a nitride semiconductor formed on the first cladding layer and containing In, a barrier layer and a well An active layer having a multiple quantum well structure in which layers are alternately stacked, a GaN layer having a Mg concentration of 1E18 cm ⁻³ or less, formed at a first temperature that is the same as a temperature at which the barrier layer is formed on the active layer, A first AlGaN layer formed on the GaN layer at the first temperature, having a first Al composition ratio of greater than 0 and less than or equal to 0.01, an Mg concentration of less than or equal to 1E18 cm ⁻³ , and a thickness less than the thickness of the GaN layer And a p-type second AlGaN formed on the first AlGaN layer, having a second Al composition ratio higher than the first Al composition ratio, and containing a larger amount of Mg than the GaN layer and the first AlGaN layer. Layers and said Formed on the 2AlGaN layer, a nitride semiconductor light emitting device characterized by comprising a second cladding layer, a having a p-type nitride semiconductor.

In a method for manufacturing a nitride semiconductor light-emitting device according to one embodiment of the present invention, a nitride semiconductor containing In is formed on a first cladding layer having an n-type nitride semiconductor, and barrier layers and well layers are alternately stacked. A step of forming an active layer having a multiple quantum well structure, a GaN layer having an Mg concentration of 1E18 cm ⁻³ or less and a first Al composition ratio of greater than 0 and 0.01 or less, and an Mg concentration of 1E18 cm on the active layer. ^-3 or less, the first AlGaN layer whose thickness is smaller than the thickness of the GaN layer in order, the same first growth temperature as the temperature for forming the barrier layer by metal organic vapor phase epitaxy, nitrogen gas atmosphere and Mg are not added And a second AlGaN layer having a second Al composition ratio larger than the first Al composition ratio on the first AlGaN layer is higher than the first growth temperature by metal organic chemical vapor deposition. First And a step of forming an atmosphere containing hydrogen gas as a main component and Mg, and a step of forming a second cladding layer having a p-type nitride semiconductor on the second AlGaN layer. A method for manufacturing a nitride semiconductor light-emitting device.

  ADVANTAGE OF THE INVENTION According to this invention, the nitride semiconductor light-emitting device from which sufficient optical output is obtained, and its manufacturing method are obtained.

Sectional drawing which shows the nitride semiconductor light-emitting device based on the Example of this invention. The figure which shows the depth profile of Mg in the nitride semiconductor light-emitting device. The figure which shows the luminous efficiency of the nitride semiconductor light-emitting device in contrast with the 1st comparative example. Sectional drawing which shows the nitride semiconductor light-emitting device of a 1st comparative example. The figure which shows the luminous efficiency of the nitride semiconductor light-emitting device in contrast with the 2nd comparative example. Sectional drawing which shows the nitride semiconductor light-emitting device of a 2nd comparative example. The figure which shows the luminous efficiency of the nitride semiconductor light-emitting device in contrast with the 3rd comparative example. Sectional drawing which shows the manufacturing process of the nitride semiconductor light-emitting device. Sectional drawing which shows the manufacturing process of the nitride semiconductor light-emitting device. Sectional drawing which shows the manufacturing process of the nitride semiconductor light-emitting device. Sectional drawing which shows the manufacturing process of the nitride semiconductor light-emitting device.

  Embodiments of the present invention will be described below with reference to the drawings.

  A nitride semiconductor light emitting device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a nitride semiconductor light emitting device.

  As shown in FIG. 1, in the nitride semiconductor light emitting device 10 of this example, a thickness of 3 μm formed on a substrate 11 transparent to the emission wavelength, for example, a sapphire substrate via a buffer layer (not shown). About a gallium nitride layer 12 (hereinafter referred to as GaN layer 12) is formed.

  On the GaN layer 12, an n-type gallium nitride cladding layer 13 (hereinafter referred to as an n-type GaN cladding layer or a first cladding layer 13) doped with silicon (Si) having a thickness of about 2 μm is formed.

  On the n-type GaN cladding layer 13, an active layer 14 having a nitride semiconductor containing In is formed. The active layer 14 includes, for example, a gallium nitride barrier layer 15 (hereinafter, GaN barrier layer 15) having a thickness of 5 nm and an indium gallium nitride well layer 16 (hereinafter, InGaN well layer 16) having a thickness of 2.5 nm. The multi-quantum well (MQW) active layers are stacked alternately and the top layer is an InGaN well layer 16. Hereinafter, the active layer 14 is referred to as an MQW active layer 14.

The In composition ratio x of the InGaN well layer 16 ((In _x Ga _1-x N layer, 0 <x <1) is set to about 0.1 so that the peak wavelength of light emission is about 450 nm, for example.

On the MQW active layer 14, a gallium nitride layer 17 (hereinafter referred to as a GaN layer 17) is formed. A first AlGaN layer 18 having a small Al composition ratio x1 (first Al composition ratio) is formed on the GaN layer 17. The composition of the first AlGaN layer can be expressed as Al _x1 Ga _1-x1 N (0 <x1 <1).

  The GaN layer 17 and the first AlGaN layer 18 are formed undoped as will be described later, and suppress thermal degradation of the MQW active layer 14 in the temperature raising step, and suppress diffusion of Mg into the MQW active layer 14. Functions as a cap layer.

  Hereinafter, the GaN layer 17 is referred to as a GaN cap layer 17, and the first AlGaN layer 18 is referred to as an AlGaN cap layer 18.

  Therefore, the AlGaN cap layer 18 effectively suppresses the thermal degradation of the MQW active layer 14 so as not to hinder the light emission efficiency, and provides a low bulk resistance so as not to hinder the operating voltage. A combination of Al composition ratio x1 and thickness that meets the requirements is required.

  The GaN cap layer 17 satisfies both requirements of absorbing diffused Mg and not hindering the function of the p-type AlGaN layer serving as an electron barrier layer for confining electrons in the MQW active layer 14 described later. Such a thickness is necessary.

  Here, the thickness of the GaN cap layer 17 is set to about 5 nm, for example. The Al composition ratio x1 of the AlGaN cap layer 18 is preferably greater than 0 and less than or equal to 0.01, for example, set to 0.003, and the thickness is set to, for example, about 1 nm.

On the AlGaN cap layer 18, Mg is doped at a high concentration, and a p-type AlGaN electron barrier layer 19 (second AlGaN layer 19) for confining electrons in the MQW active layer 14 is formed. The composition of the second AlGaN layer can be expressed as Al _x2 Ga _1-x2 N (0 <x2 <1, x1 <x2).

  The Al composition ratio x2 (second Al composition ratio) of the p-type AlGaN electron barrier layer 19 is larger than the Al composition ratio x1, for example, set to 0.1 to 0.2.

The Mg concentration of the p-type AlGaN electron barrier layer 19 is set to about 1E19 to 1E20 cm ⁻³ , for example. The thickness of the p-type AlGaN electron barrier layer 19 is, for example, about 10 nm.

On the p-type AlGaN electron barrier layer 19, a p-type gallium nitride cladding layer 13 (hereinafter referred to as a p-type GaN cladding layer or a second cladding layer 20) doped with, for example, Mg having a thickness of about 100 nm at a high concentration is formed. Is formed. The Mg concentration of the p-type GaN cladding layer 20 is set to about 1E19 to 1E20 cm ⁻³ , for example.

On the p-type GaN cladding layer 20, for example, a p-type gallium nitride contact layer 21 (hereinafter referred to as a p-type GaN contact layer) having a thickness of about 10 nm and doped with Mg at a higher concentration than the p-type GaN cladding layer 20. 21) is formed. The Mg concentration of the p-type GaN contact layer 21 is set to about 1E20 to 1E21 cm ⁻³ , for example.

  A p-side electrode 22 made of Ni / Au is formed on the p-type GaN contact layer 21. Furthermore, one side is dug from the p-type GaN contact layer 21 to a part of the n-type GaN clad layer 13, and an n-side electrode made of Ti / Pt / Au is formed on the exposed n-type GaN clad layer 13. 23 is formed. The n-type GaN cladding layer 13 also serves as an n-type GaN contact layer.

  Light is emitted from the MQW active layer 14 by connecting the p-side electrode 22 to the positive electrode of the power supply, connecting the n-side electrode 23 to the negative electrode of the power supply, and energizing.

  Here, the functions of the n-type GaN clad layer 13, the MQW active layer 14, the p-type GaN clad layer 20, and the p-type GaN contact layer 21 are well known, and the description thereof is omitted.

  In the nitride semiconductor light emitting device having the above-described structure, the GaN cap layer 17 capable of forming a thick film with good crystallinity even at a relatively low growth temperature, and the heat of the MQW active layer 14 due to the relatively high melting point and the chemical stability The p-type AlGaN electron barrier layer 19 to the p-type GaN contact layer 21 doped with Mg at a high concentration are formed by optimizing the two-layer structure with the AlGaN cap layer 18 that effectively suppresses deterioration. At this time, the thermal degradation of the MQW active layer 14 is suppressed, and the effect of preventing the diffusion of Mg into the MQW active layer 14 is enhanced.

  In order to confirm this, the result of examining the depth profile of Mg in the nitride semiconductor light emitting device 10 will be described with reference to FIG.

  Furthermore, the results of examining the influence of the GaN cap layer 17, the AlGaN cap layer 18, and the Al composition ratio x1 on the light emission efficiency will be described with reference to FIGS.

  FIG. 2 is a view showing a depth profile of Mg in the nitride semiconductor light emitting device 10. The depth profile of Mg was determined by secondary ion mass spectrometry (SIMS).

  In addition to the Mg depth profile, FIG. 2 shows a hydrogen (H) depth profile that shows the same behavior as Mg because it is combined with Mg and incorporated during film formation, and a marker for identifying each layer. The secondary ion intensity of Al and In is shown together.

  The thick solid line indicates the depth profile of Mg, and the thin solid line indicates the depth profile of H. The broken line indicates the secondary ion intensity of Al, and the alternate long and short dash line indicates the secondary ion intensity of In.

  As shown in FIG. 2, from the depth profile of the secondary ionic strength of Al and In, the interface between the MQW active layer 14 and the undoped GaN cap layer 17 is approximately 100 nm in depth from the surface (design). The value is, for example, 126 nm).

Since the slope of rise of the secondary ion intensity of Al and In (˜7 nm / decade) and the slope of fall of the Mg concentration below the background level of H concentration (˜5E18 cm ⁻³ ) are substantially equal, the MQW of Mg No significant diffusion into the active layer 14 is observed. This indicates that Mg in the MQW active layer 14 is below the detection limit.

The Mg concentration in the undoped GaN cap layer 17 and the AlGaN cap layer 18 was estimated to be 1E18 cm ⁻³ or less.

  Therefore, the diffusion of Mg into the MQW active layer 14 is effectively suppressed by the two-layered structure of the undoped thick GaN cap layer 17 and the undoped and thin AlGaN cap layer 18 having a small Al composition ratio x1. Was confirmed.

  FIG. 3 is a diagram showing the current dependence of the luminous efficiency of the nitride semiconductor light emitting device 10 in comparison with the first comparative example, and FIG. 4 is a cross-sectional view showing the first comparative example.

  The current dependence of the luminous efficiency of the nitride semiconductor light emitting device is determined by measuring the intensity of light emitted from the nitride semiconductor light emitting device using an integrating sphere while changing the current passed through the nitride semiconductor light emitting device. The strength was determined by dividing by the energizing current.

  The current dependency of the light emission efficiency of the nitride semiconductor light emitting device generally tends to decrease as the current increases except for the rising low current region. This is due to the fact that, when the current increases, the probability that the carriers injected into the MQW active layer overflow increases and the carrier injection efficiency decreases, and the internal quantum efficiency of the MQW active layer decreases due to heat generation. .

  Here, the first comparative example is a nitride semiconductor light emitting device 40 that does not have the undoped thick GaN cap layer 17 as shown in FIG. First, the first comparative example will be described. As shown in FIG. 3, the nitride semiconductor light emitting device 40 of the first comparative example showed light emission efficiency substantially equal to that of the nitride semiconductor light emitting device 10 of this example when the current was 5 mA or less. However, the luminous efficiency decreased rapidly as the current increased.

  On the other hand, in the nitride semiconductor light emitting device 10 of this example, the decrease in light emission efficiency was moderate even when the current increased, and higher light emission efficiency than that of the nitride semiconductor light emitting device 40 of the first comparative example was obtained.

  The increase rate of the luminous efficiency was about 9% when the current was 20 mA, and about 17% when the current was 50 mA. The increase rate was higher as the current was higher.

  This indicates that the undoped thick GaN cap layer 17 mainly suppresses the diffusion of Mg into the MQW active layer 14.

  FIG. 5 is a diagram showing the current dependence of the luminous efficiency of the nitride semiconductor light emitting device 10 in comparison with the second comparative example, and FIG. 6 is a cross-sectional view showing the second comparative example.

  Here, as shown in FIG. 6, the second comparative example is a nitride semiconductor light emitting device 60 that is undoped, has a small Al composition ratio x1, and does not have a thin AlGaN cap layer 18. First, the second comparative example will be described.

  As shown in FIG. 5, the nitride semiconductor light emitting device 60 of the second comparative example exhibited a luminous efficiency substantially equal to that of the nitride semiconductor light emitting device 10 of this example when the current was 10 mA or less. However, the luminous efficiency tended to decrease rapidly as the current increased.

  On the other hand, in the nitride semiconductor light emitting device 10 of this example, the decrease in light emission efficiency was moderate even when the current increased, and higher light emission efficiency than that of the nitride semiconductor light emitting device 60 of the second comparative example was obtained.

  The increase rate of the light emission efficiency was about 3% when the current was 20 mA, and about 6% when the current was 50 mA. The increase rate increased as the current increased.

  This shows that the thermal deterioration of the MQW active layer 14 is effectively suppressed even with the AlGaN cap layer 18 having a low Al composition ratio x1.

  FIG. 7 is a diagram showing the current dependency of the luminous efficiency of the nitride semiconductor light emitting device 10 in comparison with the third comparative example. Here, the third comparative example is a nitride semiconductor light emitting device having an AlGaN cap layer having a high Al composition ratio x1.

  FIG. 7 shows that the Al composition ratio x1 of the AlGaN cap layer 18 in the nitride semiconductor light emitting device 10 of this example is 0.003, and the Al composition ratio x1 of the AlGaN cap layer in the nitride semiconductor light emitting device of the third comparative example is 0. .05 is an example.

  As shown in FIG. 7, the current dependency of the nitride semiconductor light emitting device 10 of this example and the nitride semiconductor light emitting device of the third comparative example are substantially the same. However, in the entire current region, the nitride semiconductor light emitting device 10 of this example has higher luminous efficiency than the nitride semiconductor light emitting device of the third comparative example.

  The increase rate of the luminous efficiency was about 3% when the current was 20 mA and about 2.2% when the current was 50 mA, and the increase rate with respect to the current showed a substantially constant tendency.

  This is because the lower the Al composition ratio, the better the crystallinity of the AlGaN layer. Therefore, the AlGaN cap layer 18 is more effective in suppressing the diffusion of Mg into the MQW active layer 14 than the AlGaN cap layer of the third comparative example. It shows improvement.

  Thereby, by optimizing the two-layer structure of the GaN cap layer 17 and the AlGaN cap layer 18, thermal degradation of the MQW active layer 14 is suppressed, and Mg diffusion to the MQW active layer 14 is prevented. A synergistic effect was observed.

  Next, a method for manufacturing the nitride semiconductor light emitting device 10 will be described with reference to FIGS. 8 to 11 are cross-sectional views sequentially showing the manufacturing process of the nitride semiconductor light emitting device 10.

First, as a pretreatment, the substrate 11, for example, a C-plane sapphire substrate, is subjected to, for example, organic cleaning and acid cleaning, and then stored in a reaction chamber of an MOCVD apparatus. Next, the temperature Ts of the substrate 11 is raised to T0, for example, 1100 ° C. by high frequency heating in an atmospheric pressure mixed gas atmosphere of nitrogen (N ₂ ) gas and hydrogen (H ₂ ) gas, for example. Thereby, the surface of the substrate 11 is vapor-phase etched, and the natural oxide film formed on the surface is removed.

Next, as shown in FIG. 8, a mixed gas of N ₂ gas and H ₂ gas is used as a carrier gas, and for example, ammonia (NH ₃ ) gas and tri-methyl gallium (TMG) are supplied as process gases. Then, an undoped GaN layer 12 having a thickness of 3 μm is formed.

Next, as an n-type dopant, for example, silane (SiH ₄ ) gas is supplied to form an n-type GaN cladding layer 13 having a thickness of 2 μm.

Next, the supply of TMG and SiH ₄ gas is stopped while the NH ₃ gas continues to be supplied, and the temperature Ts of the substrate 11 is lowered to T 1 lower than T 0, for example, 800 ° C., and held at 800 ° C.

Next, as shown in FIG. 9, N 2 gas is used as a carrier gas, and NH ₃ gas and TMG are supplied as process gases, for example, to form a GaN barrier layer 15 having a thickness of 5 nm, in which trimethylindium ( By supplying TMI (Tri-Methyl Indium), the InGaN well layer 16 having a thickness of 2.5 nm and an In composition ratio of 0.1 is formed.

  Next, by intermittently supplying TMI, the formation of the GaN barrier layer 15 and the InGaN well layer 16 is repeated, for example, seven times. Thereby, the MQW active layer 14 is obtained.

Next, as shown in FIG. 10, the supply of TMI is stopped while the supply of TMG and NH ₃ gas is continued, and an undoped GaN cap layer 17 having a thickness of 5 nm is formed.

  Next, the supply of TMG is left as it is, trimethylaluminum (TMA) is supplied, and an undoped AlGaN cap layer 18 having an Al composition ratio x1 of 0.003 and a thickness of 1 nm is formed.

Next, the supply of TMG and TMA is stopped while continuing to supply NH ₃ gas, and the temperature Ts of the substrate 11 is raised to T 2 higher than T 1, for example, 1030 ° C., and held at 1030 ° C. in an N ₂ gas atmosphere. To do.

Next, as shown in FIG. 11, a mixed gas of N ₂ gas and H ₂ gas is used as a carrier gas, NH ₃ gas as a process gas, TMG, TMA, and biscyclopentadienyl magnesium (Cp ₂ Mg) as a p-type dopant. ) To form a p-type AlGaN electron barrier layer 19 having an Mg concentration of 1E19 to 20 cm ⁻³ and a thickness of 10 nm.

Next, the supply of TMA is stopped while continuing to supply TMG and Cp ₂ Mg, and the p-type GaN cladding layer 20 having an Mg concentration of 1E20 cm ⁻³ and a thickness of about 100 nm is formed.

Next, the supply of Cp ₂ Mg is increased to form the p-type GaN contact layer 21 having an Mg concentration of 1E21 cm ⁻³ and a thickness of about 10 nm.

Next, the supply of TMG was stopped while the NH ₃ gas was continuously supplied, and only the carrier gas was continuously supplied to cool the substrate 11 naturally. The supply of NH ₃ gas is continued until the temperature Ts of the substrate 11 reaches 500 ° C.

  Next, after removing the substrate 11 from the MOCVD apparatus, a part of the substrate 11 is removed by RIE (Reactive Ion Etching) until reaching the n-type GaN cladding layer 13, and Ti / Pt / on the exposed n-type GaN cladding layer 13. An n-side electrode 23 made of Au is formed.

  A p-side electrode 22 made of Ni / Au is formed on the p-type GaN contact layer 21. Thereby, the nitride semiconductor light emitting device 10 shown in FIG. 1 is obtained.

  When the IV characteristic of the nitride semiconductor light emitting device 10 was measured, the operating voltage when the current was 20 mA was 3.1 to 3.5V. The light output at this time was approximately 15 mW, and the peak wavelength of light emission was approximately 450 nm.

  As described above, in this example, the undoped thick GaN cap layer 17 and the undoped Al composition ratio x1 and a thin AlGaN cap layer 18 are formed at the same temperature T1 as the MQW active layer 14 is formed. ing.

  As a result, thermal degradation of the MQW active layer 14 is prevented when the temperature is increased from the temperature T1 to the temperature T2. Furthermore, when the p-type AlGaN electron barrier layer 19 to the p-type GaN contact layer 21 are formed at the temperature T2, diffusion of Mg into the MQW active layer 14 can be prevented.

  Thereby, the quality of the MQW active layer 14 is maintained. Therefore, a nitride semiconductor light emitting device that can obtain a sufficient light output and a method for manufacturing the nitride semiconductor light emitting device can be obtained.

  The film thickness of the GaN cap layer 17 and the Al composition ratio x1 and film thickness of the AlGaN cap layer 18 in this embodiment are examples. It is further desirable to optimize each of the nitride semiconductor light emitting elements within the scope not departing from the above-mentioned purpose, depending on the structure, manufacturing conditions, and the like.

  Although the case where a C-plane sapphire substrate is used as the substrate 11 has been described here, other substrates such as a substrate such as GaN, SiC, or ZnO may be used.

  Further, the plane orientation of the substrate 11 is not limited to the C plane, and other planes such as a nonpolar plane can be used.

  Although the case where the MOCVD method is used as the method for forming the nitride semiconductor layer has been described, other forming methods such as hydride vapor phase epitaxy (HVPE), molecular beam vapor phase epitaxy (MBE) Beam Epitaxy) can also be used.

Although the case where TMG, TMA, TMI, and NH ₃ are used as the process gas has been described, other process gases such as triethyl gallium (TEG) can also be used.

10, 40, 60 Nitride semiconductor light emitting device 11 Substrate 12 GaN layer 13 n-type GaN cladding layer 14 MQW active layer 15 GaN barrier layer 16 InGaN well layer 17 GaN cap layer 18 AlGaN cap layer 19 p-type AlGaN electron barrier layer 20 p Type GaN cladding layer 21 p type GaN contact layer 22 p side electrode 23 n side electrode

Claims (3)

a first cladding layer having an n-type nitride semiconductor;
An active layer having a multiple quantum well structure formed on the first cladding layer, having a nitride semiconductor containing In, and having barrier layers and well layers alternately stacked;
A GaN layer formed on the active layer at a first temperature that is the same as a temperature at which the barrier layer is formed, and having an Mg concentration of 1E18 cm ⁻³ or less;
A first AlGaN layer formed on the GaN layer at the first temperature, having a first Al composition ratio of greater than 0 and less than or equal to 0.01, an Mg concentration of less than or equal to 1E18 cm ⁻³ , and a thickness less than the thickness of the GaN layer When,
A p-type second AlGaN layer formed on the first AlGaN layer, having a second Al composition ratio higher than the first Al composition ratio, and containing a larger amount of Mg than the GaN layer and the first AlGaN layer; ,
A second cladding layer formed on the second AlGaN layer and having a p-type nitride semiconductor;
A nitride semiconductor light emitting device comprising:   The nitride semiconductor light emitting device according to claim 1, wherein the layer in contact with the GaN layer is the well layer. forming an active layer having a multiple quantum well structure having a nitride semiconductor containing In on a first clad layer having an n-type nitride semiconductor and having barrier layers and well layers alternately stacked;
A GaN layer having an Mg concentration of 1E18 cm ⁻³ or less and a first Al composition ratio of greater than 0 and 0.01 or less, an Mg concentration of 1E18 cm ⁻³ or less, and a thickness smaller than the thickness of the GaN layer on the active layer Forming a first AlGaN layer in sequence, the first growth temperature same as the temperature for forming the barrier layer by metal organic vapor phase epitaxy, a nitrogen gas atmosphere and Mg without addition;
A second AlGaN layer having a second Al composition ratio higher than the first Al composition ratio is formed on the first AlGaN layer by a second growth temperature higher than the first growth temperature by metal organic chemical vapor deposition. Forming an atmosphere containing hydrogen gas as a main component and Mg; and
Forming a second cladding layer having a p-type nitride semiconductor on the second AlGaN layer;
A method for manufacturing a nitride semiconductor light emitting device, comprising:

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